C# 精准計時之 QueryPerformanceCounter QueryPerformanceFrequency用法

C# 用法：

    public static class QueryPerformanceMethd
    {
        [DllImport("kernel32.dll")]
      public  extern static short QueryPerformanceCounter(ref long x);


        [DllImport("kernel32.dll")]
        public extern static short QueryPerformanceFrequency(ref long x);
    }

 

    static void Main(string[] args) { long stop_Value = 0; long start_Value = 0; long freq = 0; QueryPerformanceMethd.QueryPerformanceFrequency(ref freq); QueryPerformanceMethd.QueryPerformanceCounter(ref start_Value); //Fun() 需要計時方法 QueryPerformanceMethd.QueryPerformanceCounter(ref stop_Value); double time = (double)(stop_Value - start_Value) / (double)(freq); Console.WriteLine(time);//單位S  Console.ReadLine(); } 

計算所得time即為fun（）方法所消耗時間。

 

 

C++中QueryPerformanceCounter  QueryPerformanceFrequency的用法

#include "stdafx.h"
#include "windows.h"


void main()
{
    LARGE_INTEGER nFreq;
    LARGE_INTEGER nBeginTime;
    LARGE_INTEGER nEndTime;
    double time;
    QueryPerformanceFrequency(&nFreq);
    QueryPerformanceCounter(&nBeginTime);
    Sleep(1000);
    QueryPerformanceCounter(&nEndTime);
    time = (double)(nEndTime.QuadPart - nBeginTime.QuadPart) / (double)nFreq.QuadPart;
    printf("%f\n", time);
    system("Pause");
}

計算Sleep（1000）所消耗的精確時間，並非精確的1s